James Madison Dean was born at Gallipolis, County Gallia, Ohio on May 25, 1842 to John M Dean (1815–?), a farmer, and his wife Mary Polly Dean neé Waugh (1825–?). James was the first of eight children (six boys and two girls).
James was a volunteer soldier in the Civil War, enlisting at Lawrence County, Ohio on March 26, 1863. He served with the 3rd Virginia Cavalry and was wounded at the battle of Fischer and had his left leg amputated, being discharged in Philadelphia, Pennsylvania on May 30, 1865.
James married his first wife, Susan Lambert neé Anderson (1840–1883), a widow, in Lawrence County, Ohio on August 10, 1865. Susan’s first husband William Lambert was a casualty of the Civil War in 1864. James and Susan had five children
- John Anderson Dean (1866–1956)
- James M Dean (1869–1940)
- Anna Florence Dean (1875–1958)
- David Franklin Dean (1878–1930)
- Herbert Dean (1881–1910)
Susan died in Wayne County, Illinois on October 20, 1883 aged 42.
James married his second wife Nancy Bell Smothers (1863–1898) at Clay City on December 25, 1883. James and Nancy had six children, one who died at birth:
- Cora Dean (1885–1968)
- Ethel Dean (1887-?)
- Martha Dean (1888–?)
- Everett Earnest Dean (1891–1947)
- Virgil Dean (1896–?)
- Hazel Dean (1898–1898)
Nancy died in 1898.
James married his third wife Caroline Roxie "Carrie" Creekmur (1869–1963) on October 30, 1898. James and Caroline had two children:
- Joseph Wheeler Dean (1899–1983)
- Myrtle Frances Dean (1902–1999)
In 1921, James became Coroner of Clay County, Illinois.
James died on March 11, 1928 at Xenia and is buried at Powers Cemetery, Wayne County.